A185201 10^n - second largest prime less than 10^n.

5, 11, 9, 33, 11, 21, 27, 29, 71, 57, 53, 39, 137, 29, 53, 83, 23, 33, 57, 27, 113, 71, 53, 303, 321, 249, 107, 261, 53, 17, 81, 119, 47, 513, 237, 179, 123, 123, 173, 27, 203, 137, 119, 77, 119, 147, 83, 47, 183, 161, 333, 339, 611, 579

Offset

1,1

References

D. E. Knuth, The Art of Computer Programming, Second Edition, Vol. 2, Seminumerical Algorithms, Chapter 4.5.4 Factoring into Primes, Table 1, Page 390, Addison-Wesley, Reading, MA, 1981.

Links

Robert Israel, Table of n, a(n) for n = 1..1000

Formula

a(n) = 10^n - precprime(precprime(10^n)-1)

Example

a(1)=5 because precprime(10)=7, and precprime(6)=5.

Maple

seq(10^n - prevprime(prevprime(10^n)), n=1..100); # Robert Israel, May 28 2017

Mathematica

Table[10^n - NextPrime[10^n, -2], {n, 1, 50}] (* G. C. Greubel, Jun 24 2017 *)

Crossrefs

Cf. A033874.

Sequence in context: A356480 A075261 A254766 * A112956 A258995 A335554

Adjacent sequences: A185198 A185199 A185200 * A185202 A185203 A185204

Keyword

nonn

Author

Washington Bomfim, Jan 24 2012

Status

approved